1、Unit 3 The world of Science Using language：Present perfect passive1.He cleans the room every Sunday.2.What did you use it for?3.He can make some machines.4.He has already read this book.把下列句子改写为被动语态：The room is cleaned every Sunday.What was it used for?Some machines can be made.This book has already
2、 been read.被动语态的使用情况：1.不知道或者没有必要说明动作的执行者是谁；2.强调动作的承受者，而不是动作的执行者；3.动作的执行者很模糊;4.有时候为了礼貌的需要，避免说出动作的执行者。例如：1.Such books have been written for children.2.All the products have been tested.3.The letter has been opened.4.They have been told many times not to make noises.c I guess someone has asked you abou
3、t the title of your book before.d People have used new inventions like 3D printers to make replacement hearts and bone parts.a.I guess you have been asked about the title of your book before.b.New inventions like 3D printers have been used to make replacement hearts and bone parts.Compare them with
4、the following sentences and answer the questions.present perfect active formpresent perfect passive formGroup 1Group 2c I guess someone has asked you about the title of your book before.d People have used new inventions like 3D printers to make replacement hearts and bone parts.a.I guess you have be
5、en asked about the title of your book before.b.New inventions like 3D printers have been used to make replacement hearts and bone parts.Why does the author choose to use the passive form instead of the active?present perfect active formpresent perfect passive formGroup 1Group 2To emphasize the objec
6、t:“you”and “new inventions”.Present Perfect 现在完成时 (have/has+v-ed)1.表示示说话时已经完成的动作，而且这个动作的结果说话时已经完成的动作，而且这个动作的结果对现在仍有影响对现在仍有影响;I have already finished my homework.2.表示动作发生在过去，但一直持续到现在，并且有表示动作发生在过去，但一直持续到现在，并且有 可能继续持续下去可能继续持续下去。We have learned English for 7 years.Present Perfect 现在完成时 (have/has+v-ed)一般
7、和与现在有联系的时间状语(从句)连用：already,recently,lately,in recent years,so far,up to now 等during/in/over/for the last/past+时间段；for+时间段；since引导的时间状语或状语从句。have/has been done强调一个发生在过去的被动动作。强调一个发生在过去的被动动作。表示动作已经完成，对现在造成的影响或结果；表示动作已经完成，对现在造成的影响或结果；主语为动作的承受者，与谓语动词是被动关系。主语为动作的承受者，与谓语动词是被动关系。(1)These flowers have been w
8、atered,and you can go home.(2)Our classroom has been cleaned,so you neednt clean it now.The children havent been told the good news.句型转换The children have already been told the good news.将上面的句子变为否定句。_将上面的句子变为一般疑问句。_将上面的句子对the children进行提问。_ Have the children been told the good news yet?Who has been t
9、old the good news yet?1.副词的位置副词的位置often,usually,always,never,hardly,seldom等副等副词置于词置于have/has和和been中间。中间。(1)Such a man has hardly been believed.(2)The machine has already been repaired.用法及注意事项2.2.不及物动词（词组）如不及物动词（词组）如 happen,take place,die,happen,take place,die,appear appear 没有被动语态，而不及物动词加介词或者副词构成的没有被
10、动语态，而不及物动词加介词或者副词构成的短语，相当于及物动词，可以用于被动语态。注意介词和副词短语，相当于及物动词，可以用于被动语态。注意介词和副词不能丢掉。不能丢掉。e.g.e.g.孩子们这些年被王奶奶照顾得很好。孩子们这些年被王奶奶照顾得很好。The child has been taken good care of by The child has been taken good care of by Grandma Wang all these years.Grandma Wang all these years.3.3.非持续性动词，如非持续性动词，如 come,go,start,b
11、egin,leave,come,go,start,begin,leave,arrive,reach,get,marry,diearrive,reach,get,marry,die等现在完成时的被动语等现在完成时的被动语态不能和表示一段时间的状语连用。若要表达相应意思，态不能和表示一段时间的状语连用。若要表达相应意思，需改动词或时态。需改动词或时态。(1)The new car has been kept for a month.(buy)(2)How long has the meeting been on?(begin)但这类动词的否定式可表示动作的持续过程，可与但这类动词的否定式可表示动作的持续过程，可与since或或for构成的时间状语连用。构成的时间状语连用。This dictionary has not been borrowed since last week.
